Motility and ATP content of extended equine spermatozoa in different storage conditions

The role of various environmental conditions on sperm motility and ATP content was investigated by incubating raw and washed spermatozoa collected with an open-ended artificial vagina from 10 stallions in various biological and artificial media under different atmospheric conditions. Spermatozoa did not survive for more than 12 h when kept unextended in the original seminal fluid in any circumstances. The most favourable media tested for long-term sperm survival were Kenney's medium or Kenney's medium supplemented with 10 mM-theophylline and 10 mM-Hepes, pH 7.2. Centrifugation and slow cooling to 5-7 degrees C improved the survival as did incubation in atmosphere containing 5% CO2 or in a closed plastic bag with no air-space. In the most favourable circumstances, spermatozoa could stay alive, in some instances, for up to 4-5 days. The pregnancy rates 16 days after oestrus in mares inseminated with extended and cooled spermatozoa stored for 24 h were 82% (n = 11) and 70% (n = 10) per first oestrous cycle for Kenney's medium and the supplemented Kenney's medium, respectively.